Bow thruster motor.

Christopher Bromley

The Leroy-Somer bow thruster motor on my SM Pure Magic failed with sparks & some smoke from within the commutator cage. There is just one rewind facility locally which I used having heard from Amel that the motor is no longer in production, and there is no reserve stock of motors. After rewind repair of heat damaged armature windings (the field coils were also rewound because of lesser, indirect, heat damage)  the motor was demonstrated to run smoothly, both forwards and in reverse for about one to two minutes. Reinstalled on the boat, having taken every care to make the correct connections to the Albright contactors the motor ran for about a second before showering sparks. Back to the rewind facility, a second repair, followed by a successful test run  and similar failure once again. With options running out, I trespassed into the unknown and  dismantled the top end bearing housing and brush mechanism after checking for continuity ( present ) across the DI/D2 power leads which supply the field coils, but found no continuity across the A1/A2 leads for the armature windings. Checking for continuity across the commutator segments showed multiple connections between segments, but  with no ordered pattern such as you would expect if the current path follows the intended route between conductors and segments. My conclusion is the commutator is shorted in many places and I do not think this is repairable, certainly not locally. 
 I am a new recruit to the forum and have seen a wealth of input on the topic of bow thrusters, but mostly to do with the seals and servicing of the drive shaft and propeller. Somebody must have had to deal with an electric motor problem here or even had to replace the motor. I would really appreciate any advice from the experienced forum as to how to get back to a functioning bow thruster. Thank you for your help,
     Chris Bromley.

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